The present invention relates to dental attachment or anchoring structures for attaching dental appliances such as full dentures or overdenture partial dentures, and the like to a remaining non-vital root, an adjacent tooth, or to an endosseus implant.
In U.S. Pat. No. 5,417,570 of Zuest et al., a dental anchor assembly is described in which a female part for attachment to a tooth root or implant has a socket, and a male part has a first end for snap engagement in the socket and a second end in swivel engagement in a cap for securing in a recess in a dental appliance. This provides for some relative movement at both ends of the male part, reducing the risk of excessive wear and loosening of the attachment.
It has been found that, in use, it is sometimes difficult for the wearer to properly locate the female socket, so that the mating, retentive end or head of the male part may hit the edge of the female part when the wearer inserts the denture. Repeated impacts of this type may damage the retentive head of the male, reducing or losing the retention force required for proper operation of the attachment.
Other prior art attachments utilize a male head which is in releasable snap engagement with a female socket, but do not provide a double hinging action since the male part is secured in the denture cap with no freedom of movement. Also, these arrangements do not always avoid the risk of damage to the retentive head of the male due to improper alignment with the female when re-inserting the denture or appliance. U.S. Pat. No. 5,195,890 of Sulc describes an attachment in which the cap and male are formed in one part, the cap having an integral, internal projection forming the male retentive head. U.S. Pat. No. 5,556,280 of Pelak describes an attachment system in which a male member is of cup-shaped structure, with an internal projection for snap-fit retention in the female socket. The male member is embedded in a receptacle or directly in the appliance.